Startide Rising picks up about 200 years after Sundiver left off. The first mostly-dolphin starship crew is assembled and sent on a survey mission. Upon finding a huge derelict fleet of unknown origin and sending a message home about it, several hostile races hound the small survey craft until she crashes in the ocean of a metal-rich waterworld. Apparently, the hostiles are all quasi-fanatical races who believe in the eventual return of the Progenitors, the race or races who began the practice of Uplift. It soon becomes clear that the fanatics think the derelict fleet is a sign pertaining to the Progenitors, and they want the location of that fleet badly.
The Earthlings struggle to repair their ship and escape before the hostiles find them, but the untried crew must first face internal treachery as well as the mysterious hazards of the planet. They also encounter a number of oddities with the Library, the supposed sum total of all sentient knowledge, that was made available to Earth races by the Galactic civilization.
The overarcing plot of Startide Rising is fairly straightforward; it’s the subtleties of the crew’s struggles that make up the meat of the story. Brin continues with his engaging writing, and the closing sequence of the books is composed of wonderfully concerted episodes of action that make for a rousing finish. Brin spreads out his character development this time, so we have many more points of view to consider.